Machine for lapping spiral bevel and hypoid gears

ABSTRACT

A machine for lapping spiral bevel and hypoid gears, wherein the device to impart to one of the spindles thereof oscillating motion in three mutually perpendicular directions comprises three cam followers arranged on the slide block in parallel to one another, and three pairs of cams, of which each is mounted with the possibility of being imparted an independent setting motion lengthwise the geometrical axis of the cam follower interacting therewith. Each of the cam followers, while reciprocating in a direction crosswise to the geometrical axis of its own, by one of its ends alternatively interacts with the cams of its respective pair, whereas the other end thereof is kinematically associated with said spindle. As a result of the resultant motion of all the cam followers said spindle performs oscillating motion in three mutually perpendicular directions with an initial point specific to each of the face surfaces of the tooth being lapped.

United States Patent [191 Sorokovsky et a1. 9

[ MACHINE FOR LAPPING SPIRAL BEVEL AND HYPOID GEARS [76] Inventors: Vladislav Kazimirovich Sorokovsky,

ulitsa Ogorodnaya 170/2 kv. l1; Anatoly Vasilievich Bogachev, ulitsa Ogorodnaya 170/2 kv. 2; German Ivanovich Kuznetsov, Saratov llinsky proezd 11 kv. 25, all of Saratov, U.S.S.R.

[22] Filed: Dec. 16, 1971 [21] Appl. No.: 208,594

[ June26, 1973 Primary Examiner-Leonidas Vlachos Attorney-John G. Schwartz, Eric H. Waters et al.

[57] ABSTRACT A machine for lapping spiral bevel and hypoid gears,

wherein the device to impart to one of the spindles.

thereof oscillating motion in three mutually perpendicular directions comprises three cam followers arranged on the slide block in parallel to one another, and three pairs of cams, of which each is mounted with the possibility of being imparted an independent setting motion lengthwise the geometrical axis of the cam follower interacting therewith. Each of the cam followers, while reciprocating in a direction crosswise to the geometrical axis of its own, by one of its ends alternatively interacts with the cams of its respective pair, whereas the other end thereof is kinematically associated with said spindle. As a result of the resultant motion of all the cam followers said spindle performs oscillating motion in three mutually perpendicular directions with an initial point specific to each of the face surfaces of the tooth being lapped.

4 Claims, 7 Drawing Figures MACHINE FOR LAPPING SPIRAL BEVEL AND IIYPOID GEARS The present invention relates generally to gearfinishing machines and more specifically, to machines for lapping spiral bevel and hypoid gears.

The invention can find most utility when applies in automotive industry.

Gear lapping is instrumental in attaining higher quality of contact of mating profiles and tooth surface finish after final cutting and heat treatment and, as a result, better smoothness and reduced noise during the operation of a gear train.

In gear-lapping machines the gears being lapped rotate in mesh with each other while performing relative motion. As a result, the point of engagement of the teeth of the gears being lapped moves and the gears get lapped to each other.

Known in the present state of the art are machines for lapping spiral bevel and hypoid gears, wherein the bed mounts a hypoid head which carries a driven spindle to clamp one of the gears being lapped therein, a stock head carrying a driving spindle to clamp the other of the two gears being lapped, and a device to impart to one of said spindles oscillating motion in three mutually perpendicular directions, said device comprising three pairs of cams and three cam followers arranged in parallel to one another, each of said cam followers being adapted to successively interact by its one end with the cams of its respective pair, while by its other end said cam followers is mechanically coupled with the spindle imparted oscillating motion (cf. Swiss Pat. No. 381,505 protecting the model SKL gear lapping machine of the firm Erlikon).

In the machines discussed above the driven spindle receives motion from the three pairs of cams mounted in a slide block imparted reciprocating motion from a rotary former. The cams 'of each of the three pairs are located one above the other in such a way that the top cams of said pairs constitute a set of three cams effective in lapping one of the gear tooth face surfaces when the gear rotates in one direction, whereas the bottom cams are operative to perform lapping of the other tooth face surface when the gear reverses its rotation. Each of the cams is essentially two sectors contacting with each other by their vertices which, in turn, form the cam heel. Said sectors of each cam are free to rotate round their vertices for adjustment purposes so as to form an angle made up by the plane working surfaces of each sector and the direction of reciprocating motion performed by the slide block carrying said cams.

The cams act upon the cam followers mounted in the carriage in such a manner that each of the cams of one set acts upon its particular follower.

When the rotation of the gears being lapped is reversed to perform lapping of the teeth opposite surface, the carriage with the cam followers is traversed vertically so that said followers be free to engage the cams of the other set.

In these known machines each cam follower by its end opposite to that interacting with the cam is mechanically coupled with the spindle imparted oscillating motion.

Thus, the three cams of one set are capable of defining and imparting (through the cam followers and their mechanical interlinkage with said spindle carrying one of the gears being lapped) oscillating motion to the spindle in three mutually perpendicular directions. As a result of such a motion of the spindle the point of engagement of the teeth face surfaces of the gears being lapped, moves along two segments of a broken line, said segments being spatially arranged at angles defined by the arrangement of the sectors the cams are composed of. The bend point of said broken line is assumed to be referred to as the initial point. Such a position of the cam followers corresponds to that point, wherein each of these is in engagement with the vertex of its particularcam.

It is worth notice that the arrangement of the fixed cams in a common slide block is responsible for a number of disadvantages inherent in the afore-discussed machines.

A principal prerequisite of a high-quality lapping of spiral bevel and hypoid gears on the known machines resides in the necessity of a similar initial relative position of the spindles in lapping both of the tooth face surfaces which defines the position of the initial points of lapping for these tooth surfaces.

In this case the lapping cycle (viz., direct and reverse rotation of the gears being lapped, i.e., lapping of the both tooth face surfaces) occurs at the same setting-up procedure of the lapping machine.

In the case where the position of the initial points on the different sides of the tooth face surfaces will fail to ensure quality lapping in the given initial position of the spindles, such a complicated resetting of the machine is involved that practically the entire lapping cycle is subdivided into two steps so that one of the tooth face surface is lapped on one machine, while the other face surface, on another machine.

In the known machines, to desplace the point of engagement from the initial point towards the line of lapping, all the three cams of a set should be readjusted.

To change over from direct rotation of the gears being lapped to reverse rotation, the spindles of the machine should be brought to the initial point of engagement of the teeth of the gears being lapped.

Provision of a constant former that present the rate of the slide block reciprocating motion hinders the modification of said motion.

It is an object of the present invention to eliminate the disadvantages mentioned above.

It is an important object of the present invention to provide such a machine for lapping spiral bevel and hypoid gears having a device to impart to one of the spindles thereof oscillating motion in three mutually perpendicular directions, that though featuring a simpler design of said device as compared to the known machines of the same type, it would ensure high-quality lapping of the both face surfaces of the gear teeth at one cycle.

It is another important object of the present invention to provide such a machine of the character set forth hereinbefore that would be convenient and simple in operation.

In keeping with said and other objects in the hereinproposed machine its device for imparting to one of the spindles oscillating motion in three mutually perpendicular directions, according to the invention features each cam mounted with the possibility of independent setting motion lengthwise the geometrical axis of the follower interacting therewith, whereas all the cam followers are located on a slide block adapted to reciprocate in a direction square with the geometrical axes of the cam followers, the resultant motion of the latter causing said spindle to perform oscillating motion in three mutually perpendicular directions having the initial point specific for each tooth face surface being lapped.

It is expedient that the independent setting motion of each of the cams be actuated from a power jack.

It is not less expedient that the slide block reciprocations be imparted from a reversible electric motor through a kinematic chain incorporating a rack-andpinion drive whose toothed rack is made on the slide block.

In this case the length of reciprocating strokes of the slide block is to be adjusted by way of limit switches.

Due to such a construction the machine disclosed herein ensures high-quality lapping of the both tooth face surfaces at one cycle, is convenient and simple in operation.

In what follows the nature of the present invention is explained in the disclosure of its exemplary embodiment given by way of illustration to be taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a general view of a machine for lapping spiral bevel and hypoid gears, according to the invention;

FIG. 2 is a schematic plan view of a device to impart to one of the abovesaid spindles oscillating motion in three mutually perpendicular directions, according to the invention;

FIG. 3 is a section taken along line IIIIII in FIG. 2;

FIG. 4 is a perspective view showing the relative position of cams and cam followers, according to the invention;

FIG. 5 shows the position of a broken line which is an actual line of lapping, with respect to the theoretical line of lapping in the plane XZ of the rectangular coordinate system XYZ, according to the invention;

FIG. 6 shows same in the plane YZ of the coordinate system of FIG. 5; and

FIG. 7 shows a diagram of interaction of cams with cam followers traversed by the slide block, according to the invention.

Reference being now directed to the accompanying drawings, the herein-proposed machine for lapping spiral bevel and hypoid gears, incorporating mounted on a bed 1 (FIG. 1) a hypoid head A which carries a driven spindle 2 for clamping a gear 3 (FIGS. 2 and 3) being lapped, a stock head B carrying a driving spindle 4 for clamping another gear 5 being lapped, and a device C to inpart to one of the abovesaid spindles oscillating motion in three mutually perpendicular directions.

The hypoid head A is mounted in guideways and can perform vertical setting motions. The driven spindle 2 of said head has a braking device 6 (FIG. 2) to establish a required force applied to the gear 3 being machined during lapping process.

The stock head B (FIG. 3) is mounted with the possibility of setting motion on an intermediate plate 7 which, in turn, is so mounted on a plate 8 (FIGS. 1-3) as to be capable of setting motion therealong.

The stock head B (FIG. 3) may be fixed in position on the intermediate plate 7 with a clamp 9 and a bar 10 passing through the lugs of the intermediate plate 7.

The driving spindle 4 is mounted in an eccentric sleeve 11 of the stock head B and interconnected through a V-belt drive 12 with a motor 13 mounted on the stock head B to impart rotation to said spindle.

The eccentric sleeve 11 carries a toothed segment 14 which gets in mesh with a gear 15 mounted in the stock head B and therethrough with a toothed rack 16 mounted in the stock head B as well.

A device C (FIG. 4) comprises three pairs of cams 17, 18; 19, 20; and 21, 22 and three cam followers 23, 24 and 25 each of which is adapted to successively interact by its one end with the cams of the respective pair, whereas by its other end it is kinematically coupled with the driving spindle 4 (FIG. 2). In the hereinconsidered particular case, it is the driving spindle 4 that performs oscillating motion.

According to the present invention, each of the cams 17 through 22 is mounted on the bed 1 with the possibility of performing an independent setting motion lengthwise the geometrical axis of the cam followers 23, 24, 25.

The cams 17 through 22 (FIG. 4) are so arranged on the bed that the top cams 17, 19 and 21 of each pair form a set effective in lapping one of the face surfaces of the teeth being lapped, while the bottom cams 18, 20 and 22 form another set operative to lapping the other teeth face surface.

Each of the cams is composed essentially of two sectors mounted in a carrier 26 (FIGS. 2, 3 and 4) so as to contact each other with their vertices which, in turn, form the vertex of the cam. Said sectors are capable of setting rotation round their vertices.

Independent setting motion of each cam is actuated from power jacks 27 whose length of stroke is adjusted by stops 28 (FIGS. 3 and 4, the latter Figure showing only one stop).

Each pair of cams is located against its particular follower, viz., the pair of cams 17, 18 (FIG. 4) against the follower 23, the pair of cams 19, 20 against the follower 24 and the pair of earns 21, 22 against the follower 25.

All the three cam followers are located, according to the invention, on the slide block 29 adapted to reciprocate in the direction D perpendicular to the geometrical axes of the cam followers.

According to the invention, the slide block 29 (FIG. 2) carrying the cam followers 23 through 25 is connected to a reversible electric motor 30 through a kinematic chain incorporating a worm 31 and a worm wheel 32, a gear 33 set coaxially with said worm wheel 32 so as to mesh a toothed rack 34 provided on the slide block 29.

Adjustable pins 35 (FIG. 2) of the limit switches (not shown) are to set the length of stroke of the slide block 29 reciprocations.

Kinematic chain interlinking the cam follower 25 (FIG. 3) and the driving spindle 4 incorporates a first intermediate follower 36, a toggle arm 37, a second intermediate follower 38, the toothed rack 16, the gear 15 and the toothed segment 14 of the eccentric sleeve 11 of the driving spindle 4. w

Free plays and backlashes in the kinematic train the pair of cams 21 and 22, the cam follower 25, the first intermediate follower 36, the toggle arm 37, the second intermediate follower 38, the toothed rack 16, the gear 15, the toothed segment 14 are taken up due to turning of the eccentric sleeve 11 round its geometrical axis under the action of a spring 39.

Kinematic chain interlinking the cam followers 23, 24 (FIG. 2) and the driving spindle 4 comprises respectively intermediate followers 41 and 42 adapted to act upon the parallel-crank mechanism consisting of arms 43, 44, 45 and 46. The arms 45 and 46 are mounted on the bed with the possibility of swinging motion round their respective pivots 47 and 48 and are articulated to each other through a link 49 loaded by a spring 50.

The arms 43 and 44 are mounted on the arms 45 and 46 so as to be free to swing about their respective pivots 51 and 52 and are articulated to each other through a link 53 actuated by a spring 54; besides, the arms 43 and 44 carry respective pins 55 and 56 adapted to engage into the plate 8.

Work on the machine is carried out as follows.

By rotating an adjusting screw 57 (FIGS. 1 and 3) the intermediate plate 7 with the stock head B mounted thereon is traversed along the plate 8 in the direction shown by the arrow B (FIG. 3) to a position corresponding to the center distance of the spiral bevel gears 3 and 5 being machined.

In case of hypoid gears, an ajusting screw 58 (FIGS. 1 and 3) is to be rotated to traverse the hypoid head A in the direction indicated by the arrow F (FIG. 3) to a position corresponding to the amount of hypoid offset of the gears being machined.

Then the gears 3 and 5 are clamped on the driven spindle 2 and the driving spindle 4, respectively due to which said gears are referred to as the driven and the driving ones.

Further, a power jack 59 actuates the plate 7 to travel towards the hypoid head A, said plate, while travelling, acts upon a spring 60 which, in turn, exerts pressure upon the stock head B (mounted on the plate by means of rolling-contact bearings) thus urging it to travel likewise towards the hypoid head A.

Once the gears 3 and 5 being lapped have got in backlash-free mesh with each other, the stock head B is stopped, while the intermediate plate 7 keeps moving until the power jack 59 (FIG. 3) completes its working stroke while acting against the tension of the spring 60. At the same time the bar slides in the clamp 9 and the plate 8 is kept against moving by a stop 61.

Upon completion of the working stroke of the power jack 59 the stock head B is fixed on the intermediate plate 7 by virtue of the bar 10 getting locked by the clamped 9 through the action of a power jack 62.

Thereupon a clearance G(FIG. 2) is established in between the respective cam 19 or 20 (FIGS. 2, 4) and the camfollower 24 with the use of the power jack 27 and the stop 28, said clearance is to define the amount of backlash between the face surfaces of the gear teeth being lapped.

Insofar as the three pairs of cams 17, 18; 19, 20; and 21, 22 constitute a single set of the three cams 17, 19 and 21 which is effective in lapping one teeth face surface, and another set of cams 18, 20 and 22 effective in lapping the other face surface of the gear teeth, thus the operation and adjustment of only one of the abofesaid sets of cams, viz., that of cams 17, 19 and 21, will hereinafter be considered in the present disclosure. Accordingly, the operation and adjustment of the other set of cams 18, 20, 22 is similar to that discussed here and hereinbelow.

Once the stop 61 (FIG. 3) having been released, the link 53 is urged by the spring 54 (FIG. 3) to move towards the cam 19, thus acting upon the intermediate follower 41 and therethrough upon the cam follower 24 until the clearance G between the cam follower 24 and the cam 19 is completely eliminated (taken up). The arms 43 and 44 swing round their pivots 51 and 52 and the pins 55 and 56 mounted on the arms 43 and 44 and engaged into the plate 8, cause the latter together with the intermediate plate 7 carrying the stock head B, to travel along the axis of the driven spindle 2, whereby a backlash is established between the face surfaces of the teeth of the gears 3 and 5 being lapped.

Thus, the amount of backlash effective between the face surfaces of the teeth being lapped in the hereinproposed machine is established in the course of setting up procedure of the device C which made it possible to dispense with a highly complicated mechanism provided in the known machines specially for establishing the gear backlash.

Lapping of the gears 3 and 5 (FIGS. 2 and 3) starts with energizing the drive electric motor 13 of the driving spindle 4 and the reversible electric motor 30 of the device C.

The driving spindle 4 receives rotation from the motor 13 via the V-belt drive 12. As a result, the gear 5 clamped on the spindle 5 starts rotating, thus setting in rotation the other gear 3 clamped on the driven spindle 2 and meshed therewith, by overcoming the drag or brake torque developed by the braking device 6 (FIG. 2) which acts upon the spindle 2.

The slide block 29 (FIG. 2) receives reciprocating motion in the direction D from the reversible electric motor 30 via the toothed rack 34 made fast thereon, the gear 33, the worm wheel 32 and the worm 31.

The cam follower 25 (FIG. 3) while interacting with the track surface of the cam 21, is imparted reciprocating motion in a direction square with that of the slide block 29 travel, thus transmitting motion through the first intermediate follower 36, the toggle arm 37, the second intermediate follower 38, the toothed rack 16, the gear 15, the toothed segment 14, to the eccentric sleeve 11 in which the driving spindle 4 is mounted.

Due to this, the eccentric sleeve 11 performs rocking motion about its geometrical axis 40 together with the spindle 4. Since the geometrical axis 63 of the spindle 4 is arranged eccentrically with respect to the rocking axis 40 of the eccentric sleeve 11, the spindle 4 likewise performs rocking motion about the axis 40, which motion due to its being insignificant, is assumed as rectilinear one. In FIGS. 5 and 6 said motion corresponds to the coordinate Z of the rectangular coordinate system XYZ.

Reversing of the electric motor 30 and changing of the length of the reciprocating travel of the slide block 29 are effected by resetting the adjustable pins 35 lengthwise the slide block 29, said pins acting upon the limit switches (not shown in Figure) in the course of the slide block 29 reciprocations.

The cam follower 24 (FIG. 2), while interacting with the track surface of the cam 19, acts upon the intermediate follower 41, the arm 43, the link 53 and the arm 44, thus causing the arms 43 and 44 to swing round their respective pivots 51 and 52 on the arms 45 and 46. As a result, the pins 55 and 56 mounted on the arms 43 and 44 likewise perform swinging motion together therewith. Said swinging motion being insignificant, it

is assumed as rectangular one occurring in the direction of the axis of the cam follower 24 and represented in FIG. 6 as the coordinate Y in the rectangular coordinate system XYZ. The pins 55 and 56 engaging into the plate 8 which carries the intermediate plate 7 and the stock head B with the spindle 4, cause the latter to perform swinging motion in the same direction.

The cam follower 23, while interacting with the track surface of the cam 17 (FIG. 2), acts upon the intermediate follower 42, the arm 45, the link 49 and the arm 46, thus causing the arms 45 and 46 to swing about their respective pivots 47 and 48 mounted on the bed 1.

Swinging motion of the arms 45 and 46 are transmitted through the pivots 51 and 52 to the arms 43 and 44, thus causing the latter to perform approximately rectilinear reciprocating motion in the direction of the slide block 29 reciprocations. The pins 55 and 56 mounted on the arms 43 and 44, while performing the same reciprocations, transmit these to the plate 8, the intermediate plate 7 and the stock head B carrying the spindle 4. In FIG. to said motion corresponds the coordinate X in the rectangular coordinate system XYZ.

Thus, as a result of reciprocations performed by the slide block 29 lengthwise the track surface of the cams l7, 19, 21 in the direction perpendicular to the geometrical axes of the cam followers, the driving spindle 4 is imparted oscillating motion in three mutually perpendicular directions corresponding to the coordinates X, Y and Z in the rectangular coordinate system XYZ.

Let us consider now motions performed by the point of engagement of the face surfaces of the teeth being lapped as a result of the above-discussed motions of the driving spindle.

Represented in FIGS. 5 and 6 is the spatial theoretical curve AOB shown in two projections in the rectangular coordinate system XYZ, which curve must be traced by the point of engagement of the face surfaces of the teeth being lapped during oscillation motion of the spindle.

In the heretofore-known machines said theoretical curve is substituted, for the sake of more approxima-' tion thereto, by two straightsegments A0 and OB drawn from the point 0 which is essentially the initial point of engagement of the face surfaces of the teeth being lapped, lying on the theoretical line of lapping. In this case the actual line of lapping has three points A, O and B intersection with the theoretical lapping curve.

According to the invention disclosed herein, the actual line of lapping may have four com'mon points with the theoretical curve, viz., A, C, D and B, since the initial point 0 of engagement of the face surfaces of the teeth being lapped may be displaced in either direction off the theoretical curve to provide the maximum approximation of the actual line of lapping thereto.

The cams 17, 19 and 21 (FIG. 7) are so mounted in the bed that the lines of interaction of the earns 17, 19 and 21 with the respective cam followers 23, 24 and 25 are essentially two strainght-line segments having a common point 0 While interacting with the cam followers 23, 24 and 25 movably mounted in the slide block 29, the cam tracks determine the values X Y and Z (FIGS. 5, 6) of displacement of the point of engagement of the face surfaces of the gear teeth being lapped, which, on a definite scale correspond to the values X Y and Z of displacement of the points of interaction of the cam followers 23, 24 and 25 with the tracks of the cams 17, 19 and 21.

According to the invention, each of the cams 17, 19 and 21 may have the setting motion X Y, and Z, (in a special case presented in FIG. 7, Y, is equal to zero) directed along the axis of the respective cam follower 23, 24 and 25, said setting motion causing, on a definite scale, a displacement of the initial point 0 (FIGS. 5 and 6) of engagement by the corresponding values X Y1 and Z1 The cluster of cams 18, 20 and 22 is used for lapping the other face surface of the gear teeth being machined.

To this end, the cams 17, 19 and 21 of the first cluster must be disengaged, by means of the respective stops 28, from contact with the respective cam followers 23, 24 and 25, and the cams 18, 20 and 22 of the second cluster be brought into engagement, by means of the same stops 28 and the power jacks 27, with said cam followers.

According to the invention disclosed herein, due to the provision of an independent setting motion of each cam, one can select the positions of the initial points of engagement on the both face surfaces of the teeth being lapped independently of each other in such a manner that in each case the actual line of lapping have the maximum approximation to the theoretical curve of lapping.

What is claimed is:

l. A machine for lapping spiral bevel and hypoid gears, comprising: a bed; a hypoid head carrying a driven spindle to clamp one of the gears being lapped therein, said head being mounted on said bed; a stock head carrying a driving spindle to clamp the other gear being lapped therein, said stock head being likewise mounted on said bed; a means to impart to one of said spindles oscillating motion in three mutually perpendicular directions; said means comprising: three pairs of cams located on said bed; three cam followers arranged in parallel to one another; a slide block carrying said cam followers and adapted to reciprocate in a direction crosswise to the geometrical axes of said cam followers; each cam of said pairs of cams being mounted on said bed so as to perform independent setting motion lengthwise the geometrical axis of one of said cam followers corresponding to its particular pair of cams; each of said cam followers, while reciprocating together with said slide block, by one of its ends alternatively interacts with said cams of its respective pair of cams, whereas by its other end kinematically associated with said driving spindle, said cam follower imparts to the latter a motion; as a result of the resultant motion performed by all said cam followers, said driving spindle performs oscillating motion in three mutually perpendicular directions with an initial point specific to each face surface of the tooth being lapped.

2. A machine as claimed in claim 1, wherein the independent setting motion of each cam is actuated by a power jack.

3. A machine as claimed in claim 1, wherein the reciprocating motion of the slide block carrying the cam followers is imparted from the reversible electric motor through a kinematic train incorporating a rack-andpinion drive whose toothed rack is made on said slide block.

4. A machine as claimed in claim 3, wherein the length of reciprocating strokes performed by the slide block is adjusted by limit switches. l 4 at I 

1. A machine for lapping spiral bevel and hypoid gears, comprising: a bed; a hypoid head carrying a driven spindle to clamp one of the gears being lapped therein, said head being mounted on said bed; a stock head carrying a driving spindle to clamp the other gear being lapped therein, said stock head being likewise mounted on said bed; a means to impart to one of said spindles oscillating motion in three mutually perpendicular directions; said means comprising: three pairs of cams located on said bed; three cam followers arranged in parallel to one another; a slide block carrying said cam followers and adapted to reciprocate in a direction crosswise to the geometrical axes of said cam followers; each cam of said pairs of cams being mounted on said bed so as to perform independent setting motion lengthwise the geometrical axis of one of said cam followers corresponding to its particular pair of cams; each of said cam followers, while reciprocating together with said slide block, by one of its ends alternatively interacts with said cams of its respective pair of cams, whereas by its other end kinematically associated with said driving spindle, said cam follower imparts to the latter a motion; as a result of the resultant motion performed by all said cam followers, said driving spindle performs oscillating motion in three mutually perpendicular directions with an initial point specific to each face surface of the tooth being lapped.
 2. A machine as claimed in claim 1, whereiN the independent setting motion of each cam is actuated by a power jack.
 3. A machine as claimed in claim 1, wherein the reciprocating motion of the slide block carrying the cam followers is imparted from the reversible electric motor through a kinematic train incorporating a rack-and-pinion drive whose toothed rack is made on said slide block.
 4. A machine as claimed in claim 3, wherein the length of reciprocating strokes performed by the slide block is adjusted by limit switches. 